Dr. Peter H. Weston
A new species of Eidothea, a genus of rainforest trees that was only named in 1995, was discovered in the Nightcap Range, near Lismore in north eastern New South Wales in September 2000. Eidothea, which is up to 40 m tall belongs to the plant family Proteaceae, which also includes more familiar members such as the waratahs, grevilleas, banksias, macadamias and proteas. Eidothea zoexylocarya, the only other species, is known only from Mt Bartle Frere, near Cairns in North Queensland. The discovery of another species in N.S.W. is exciting for a number of reasons.
The Proteaceae is a very old family of flowering plants that probably originated while the ancient supercontinent Gondwana was still in one piece. Gondwana consisted of what are now the continents of Australia, Africa, South America and Antarctica, as well as smaller bits and pieces such as New Zealand, New Caledonia and Madagascar. Gondwana began splitting up over 120 million years ago and the fragments carried a diverse array of plants and animals with them, including a variety of lineages of the Proteaceae. Eidothea is the only relic of one of those early lineages that has barely survived in the rainforests of eastern Australia. Other lineages went on to diversify spectacularly, resulting in hundreds of descendant species.
Why didnt Eidothea flourish like those others? One possible explanation is that it was incapable of adapting to changing environments. We know that its appearance has not changed much for a long time because fossil fruits that look just like those of living Eidothea are known from rocks that are 15-20 million years old.
That Eidothea has been found at localities as far apart as Cairns, Lismore and Ballarat, also underlines the fact that Australias rainforests are tiny remnants of ancient rainforests that covered vast areas of Australia until only a few million years ago. This makes them a particularly precious part of our natural heritage. Similar distributions are found in a whole range of other plants and animals that are now restricted to small rainforest pockets along Australias eastern margin from Tasmania to North Queensland.